Vienna bets on solar to reach passive energy standards

For the ninth consecutive year, Vienna has been selected as the best world capital for quality of life. Yet the city is not planning to rest on its laurels for the next years; on the contrary, ambitious international projects, such as the EU-GUGLE and Smarter Together initiatives are currently running to make of the Austrian capital a “Smart City”. Throughout these projects, the municipality is implementing key actions to support clean mobility, energy-efficient building renovation and local renewable energy production. To make this happen, four local partners are combining their expertise within the EU-GUGLE project: Wiener Wohnen, the company owning the public buildings of Vienna, MA20, the city’s committee for energy planning, as well as Clean Energy Solutions, a competence centre focused on sustainable development, and experts from the University of Natural Resources and Life sciences of Vienna.

In the framework of this Smart City Initiative, the district 14, Penzing, has been selected for the development of local energy efficient retrofitting projects. As the fourth biggest district of the city, Penzing is historically the living place of workers, gathering active populations, families and retired people with low or modest revenues. As part of the EU-GUGLE, 18 buildings, including residential and social housing complexes as well as a nursing home, covering a total surface of 67.000 square meters, will be retrofitted to reach nearly zero to passive energy standards. Since the beginning of the project in 2014, renovation works have been completed in already half of the buildings selected, while nine others will be refurbished by the beginning of 2019. Altogether, a budget of 4,2 million euro will be invested in the district to make this project a reality.

Sun and energy efficiency: two sides of the same coin

To combine energy efficient retrofitting with renewable energy integration the municipality of Vienna is looking at innovative technologies, such as multifunctional prefabricated façades. In one building, a prefabricated façade associating natural insulation material with solar panels is currently being installed. The façade is composed of a wood construction with an internal honeycomb structure made of cardboard, closed by glass panels incorporating transparent solar cells. Thanks to its vertical exposition, the honeycomb structure absorbs more sunshine in winter, heating the wall located behind. At the same time, the energy of the sun is captured through the integrated solar panels, also reaching their maximum efficiency during the cold season to power the building’s new heat recovery ventilation system. In summer at the contrary, the structure creates shade for the building, keeping a fresh atmosphere for its inhabitants. Additionally, the newly installed façade has increased sound insulation properties to protect the occupants from traffic noise.

Further to this solution, the city of Vienna is also testing the combination of photovoltaic systems with heat pumps to supply the district heating network with green energy. “Once tested and validated, all these applications will create multiple opportunities for the replication of energy efficient renovation and local renewable energy production projects in the capital”, says Stefan Sattler, Manager of the Green Building Solutions programme at the University of Natural resources and Life sciences in Vienna. With so many sustainable initiatives under way, Vienna is already in good position to keep its rank as best place in the world to live for the tenth year in a row.